Can I just check how the autofocus is for other people?

I get a lot of pulsing even with a static camera aiming at a fairly easy target (without any obstructions). And when shifting the camera onto a different object the focus often shunts ALL the way to the near-focus(?) end before focusing back out to where it should be.

When it does operate normally the IAF usually throws it too far, and the AF has to back it up a bit (which looks fairly ugly and makes it unusable in-vision). And then sometimes it it just sits there doing nothing for a few seconds and takes up to 8 seconds to get focus.

Now I normally work with AF off (of course) but pressing the AF button can take up to 8 seconds to get a lock makes it fairly useless.

I'm guessing this isn't usual behaviour...?

What frame rate are you shooting in? I can't say for sure on the new XH cameras because they have the hybrid AF system. However, on the XL2 and the XLH1, the image on the CCD block is what AF uses and is not very good when the camera is at 30P or 24P because the CCD block gets clocked at slower rates and doesn't get enough motion sampling updates to autofocus reliably.

Also, the CCD based autofocus wants good light and scenes which have some vertical objects with decent contrast (which goes back to the ample light thing).

Just some food for thought, maybe it will help.

-gb-

Somebody say it ain't so.

I'm just about to FINALLY upgrade from my old XL1 with its built-in focus problems. In the posts I've read so far, folks seem to like the focus so I thought the A1 was for me, but ....

My Auto focus worked on a hand held studio shot with only 2 25 watt lamps on. I don't know if that's good but it worked for me
John

What frame rate are you shooting in? I can't say for sure on the new XH cameras because they have the hybrid AF system. However, on the XL2 and the XLH1, the image on the CCD block is what AF uses and is not very good when the camera is at 30P or 24P because the CCD block gets clocked at slower rates and doesn't get enough motion sampling updates to autofocus reliably.


Thanks Greg, I'm shooting 25F, but as I understood it the point of the IAF was to get into the right ball-park with the focus so you weren't waiting for the CCD.

The thing that worries me is the fact that sometimes the focus shunts all the way to one end and then back again, and other times the IAF just sits there doing nothing. 8 seconds is a hell of a long time for ANY autofocus system to wait to get a lock.

I was testing this in the house (fairly bright, daytime), but I think I'm going to go and find out what it's like outside.

A bit of a play outside seems about the same. Sometimes the Instant Auto Focus seems to work and sometimes it sits there doing nothing or focuses in totally the wrong direction before getting it right.

Performance is similar with Normal Auto Focus turned on, except slower to find a lock.

Also, it won't hold focus through the zoom range, flicking in and out of focus through the zoom, especially on a faster zoom setting. This was tested by focussing on a nice contrasty poster on the wall of a well lit room about 4m/12ft away (without any foreground obstructions). I allowed the camera to focus, zoomed halfway out, paused, and then zoomed back in again. Through the range it repeatedly gets sort of "kicked" out of focus, then refocuses. By the time you get back zoomed in, the poster is out of focus and takes a moment to get focus back.

Has anyone else experienced this?

"Also, it won't hold focus through the zoom range, flicking in and out of focus through the zoom, especially on a faster zoom setting. This was tested by focussing on a nice contrasty poster on the wall of a well lit room about 4m/12ft away (without any foreground obstructions). I allowed the camera to focus, zoomed halfway out, paused, and then zoomed back in again. Through the range it repeatedly gets sort of "kicked" out of focus, then refocuses. By the time you get back zoomed in, the poster is out of focus and takes a moment to get focus back."

Aaaggghh. This is what the XL1 does. Please tell me this was fixed on the XH-A1 and that we're hearing about one that needs to be returned to the shop.

I have not experienced the issue you are describing. My A1 gets focus almost instant and keeps it. You might have a lemon.

Thanks Cody, that's what I wanted to hear (I didn't fancy trying to work with this).

I suspect the root cause of the matter is something to do some sort of automatic back-focus adjustment - although that wouldn't explain why it holds focus in MF...

Time to get it swapped out! And to think, I spent 3 hour sitting in a traffic jam picking this one up on Friday!

I know what is being described as "pulsing" is. I have seen it, but the phenomena only happened for me in very dim light. It happened, but I can't just reproduce it at will. As for the failure to lock focus onto an object I have seen that too, but again was a consequence of very dim lighting, or strong backlighting through a window, etc.

Alex, in my use the focus has been robust and reliable, with no negative behavior whatsoever in strong light, and very excellent in dim light. I am not able to induce hunting at will, although I have seen it happen once or twice.

In totality, makes me think yours should be inspected by Canon.

Do you have a filter in front of the lens?

Thanks Tom,

No filter in front of the lens. I was testing in both indoor daylight (well exposed at about F4), and outdoor (again plenty bright enough), so I don't think it's a low light issue.

I wouldn't mind hunting occassionally, but every fourth focus this one seems to shunt totally to the wrong end of the focus range and then back again, or it just sits there doing nothing at all.

And the pulsing is pretty contstant, especially whilst zooming.

Hi. My A1 seems, er A1! No focus issues. In fact it seems better than my XL2 with stock lens. Trot back to the dealer quick and compare it to another unit.
Regards,
Oliver Horn.

"Also, it won't hold focus through the zoom range, flicking in and out of focus through the zoom, especially on a faster zoom setting. This was tested by focussing on a nice contrasty poster on the wall of a well lit room about 4m/12ft away (without any foreground obstructions). I allowed the camera to focus, zoomed halfway out, paused, and then zoomed back in again. Through the range it repeatedly gets sort of "kicked" out of focus, then refocuses. By the time you get back zoomed in, the poster is out of focus and takes a moment to get focus back."

Aaaggghh. This is what the XL1 does. Please tell me this was fixed on the XH-A1 and that we're hearing about one that needs to be returned to the shop.

Not being able to focus while zooming on the XL1, XL2, XLH1, and these new cameras is the result of having only a single motor that does double duty. You can't focus and zoom at the same time even if you're in manual mode. So that isn't actually a problem.

If you are not trying to zoom and just moving the camera around, the focus should track. If it doesn't, you've got a problem.

-gb-

Not being able to focus while zooming on the XL1, XL2, XLH1, and these new cameras is the result of having only a single motor that does double duty. You can't focus and zoom at the same time even if you're in manual mode. So that isn't actually a problem.
-gb-

Yipes, I didn't realize that! I'm pouting big time. It is actually a problem for me.

I shoot events and need to pan & zoom constantly, sometimes quickly sometimes slowly. Will the XH-A1 hold focus through a zoom on the same subject? Can I put focus or zoom in a fixed or manual mode and change the other?

My XL-1 won't hold focus through a zoom no matter what! It requires extensive post to cover.

Are there any new HDV cameras that can do what I want?

(Putting credit card away)

My XL-1 won't hold focus through a zoom no matter what!

You have a back focus or 'flange back' adjustment issue. On the XL1, XL2, these are not user level adjustments. The XLH1 has both manual and auto back focus adjustments. I believe the new XH series have auto FB adjustment only because it's a non removable lens.

Higher end lenses and the old Canon manual 14X and 16X have external manual adjustments.

You could send your XL1 lens in to Canon and they can set it. Don't know how much it will cost though.

-gb-

Not being able to focus while zooming on the XL1, XL2, XLH1, and these new cameras is the result of having only a single motor that does double duty. You can't focus and zoom at the same time even if you're in manual mode. So that isn't actually a problem.

But the problem happens when the camera and target are both static. Zoom in, let the camera get focus, zoom out and in again, and the camera is out of focus. If it happened in MF as well I'd say it was a back focus problem, but in MF focus holds.

In AF the whole image pulses in and out of focus as you zoom in or out - especially on the long end of the lens.

--------

Edit: Oh wait, read the post, Alex!... Your comments were about the XL1, XL2 and H1... (not the A1)

You could send your XL1 lens in to Canon and they can set it. Don't know how much it will cost though.
-gb-
Actually, I've had it in a couple of times, first on warranty then for cash, - didn't help. Blown a pixel finally so I've got to replace it. Fixing blown pixels in post in addition to covering out-of-focus zooms gets to be a real drag.

Before the XL-1 I had an old Panasonic 2 chipper designed for svhs. Zoom was powered, but everything else was manual. Could do just what I wanted. (Of course looking at old svhs tapes, I can't believe how bad that resolution was, - good grief!)

Here's a quick clip of the pulsing in action. It's fairly low light in this clip, but exactly the same happens in normal light too.

You can see as I zoom in the background pulses in and out of focus.

Hi Alex. I saw a demo of the A1 here in Singapore on Thursday evening, and noticed that the autofocus was hunting quite a bit when the sales guy was moving things around. The lighting was very dull so this wasn't really unexpected, but it does seem to mean that we'll still need to use manual focus when we need reliability. Looks to me like the new focus system is not enough of an improvement for shooting in low light conditions.

Om a more positive note, I thought the image from the camera was fabulous, the colours had a very nice richness to them, even though the lighting was poor.

Richard

That was hunting! I have had mine hunt a little, but not that bad. I like to use manual when possible, but the instant autofocus shouldn't be doing that.

I don't know what to tell you.

That's wicked bad. What were your other settings, aperture, shutter etc.?

It seems to "hunt" whenever you operate the zoom. It's like the zoom is somehow interfering with the IAF. At the start of the shot where I'm not zooming the focus is solid. But as the zoom creeps forward I can feel the AF shunting.

25F; 1/50th; Aperture as wide open as it will go. 6dB of gain in this case ('cause it was dark) but it did the same with 0dB and -3dB of gain during the day.

I'm going to speak to the dealer and get it changed on Monday.

I'm able to reproduce exactly that kind of hunting (PAL A1), but only when there's very dim light and objects are dark colour. Even then it's quite hard to get focus to hunt, but I have seen this couple of times.
But it really shouldn't appear in normal light. So I quess this isn't normal.

I did a slow zoom from a 5-6 feet of an object on the carpet in very dim light with IAF on starting at 1/60 F1.6 (the aperture opens up as I zoom), 12db gain and I could not get it to hunt.

It almost seemed like your cam couldn't decide whether to focus on the black bag or the angled floor slats behind, and dithered between them, a behavior consistent with two possibilities:

1.) IAF was not on or not working
2.) The minimum focusing distance increases as it zooms toward the telephoto end, making a lock more difficult.

Either way, it is severe and dithers much worse than I have observed under any condition. I would return the cam for replacement or service.

It's till not possible to develop an idiot proof camera then?

Read page 36 of the manual. That camera-focus clips has ALL the features required to throw the auto focus off.

I am amazed that you would expect better! A dark featureless blob on featureless background under poor lighting is probably something the Canon engineers hadn't planned for...

If you must record something like that first zoom in, focus up with either manual or temp AF, zoom out. Then record your zoom making sure that the camera is not in AF beforehand.

To rely on auto focus during a zoom in is an amateurish technique doomed to failure and does not reflect on the camera but the person using it.

Sorry to be blunt but the XH-A1 is a wonderful piece of kit in the right hands.

TT

Sorry Tony but I think the issue is something wrong with his cam. The discussion of shooting style, subject matter is not germaine to the auto focus problem. Alex has stated the cam does this in quite a few situations, presumably even the ones not limited to page 36 of the manual.

But be glad, the Canon Zoom lens is a Parfocal (...if it is...), because if not, the focus plane will change with zoom length as it does on many DSLR lenses, in which case a technique of zooming in to lock manual focus before zooming back out will result in an out of focus image.

But be glad, the Canon Zoom lens is a Parafocal (...if it is...), because if not, the focus plane will change with zoom length as it does on many DSLR lenses, in which case a technique of zooming in to lock manual focus before zooming back out will result in an out of focus image.

IF IT IS ???? Could someone PLEASE say more about this? Please? Please?

The discussion of shooting style, subject matter is not germaine to the auto focus problem.Completely disagree. Actually it has everything to do with it. As Tony pointed out above, there are certain situations in which AF cannot be expected to function properly. These include shooting toward reflective surfaces, subjects with low contrast or without vertical lines, fast moving subjects, shooting through dirty or wet windows, and night scenes. "Additionally, in 30F and 24F mode, autofocus takes longer than in the 60i mode. When recording under dark conditions, the focusing range narrows and the picture may appear blurred. Autofocus may not work well on the following subjects. In that case, focus manually." All of this is verbatim from the operator's manual.

This goes beyond just the simple understanding that AF needs contrast (and therefore light) in order to work properly. There are bright-light situations that can confuse AF as well.

As far as hunting during a zoom, that won't happen if critical focus is established first.

Yes I think Alex should absolutely go ahead and have his camera checked out by Canon UK's service department. I would be very interested to know the results. Nothing is going to be properly diagnosed on an internet message board. All we're capable of doing here is to give Alex the best possible advice, which is, get the camera checked by Canon service.

Sorry Tony but I think the issue is something wrong with his cam. The discussion of shooting style, subject matter is not germaine to the auto focus problem. Alex has stated the cam does this in quite a few situations, presumably even the ones not limited to page 36 of the manual.

But be glad, the Canon Zoom lens is a Parafocal (...if it is...), because if not, the focus plane will change with zoom length as it does on many DSLR lenses, in which case a technique of zooming in to lock manual focus before zooming back out will result in an out of focus image.

I think you mean Parfocal. ;) If it's not parfocal then it's useless.

Having seen the clip I don't think it is symptomatic of a camera problem. If there are well lit situations where a subject should be AFed without a problem then let's see it. I don't think the clip shows anything that wouldn't be expected of many cameras.

As Tony pointed out above, there are certain situations in which AF cannot be expected to function properly.

Chris, I'm just saying I shot that same thing to test and didn't remotely get that herky jerky jumping jack autofocus hunting problem. Try duplicating it and see if you do.

Chris, I'm just saying I shot that same thing to test and didn't remotely get that herky jerky jumping jack autofocus hunting problem. Try duplicating it and see if you do.Sorry Tom, I should have stated this earlier... I've handled several different A1s now and none of them exhibited any sort of unexpected behavior in AF or IAF.

AF working fairly well for me. I have AF selected in my menu as opposed to IAF. Makes a difference in certain lighting conditions. Accurate focus in wide angle from a few inches to infinity. Hunts a bit zoomed in on anything less than a few feet away. I try not to use AF unless I have to.